The present invention relates to three-dimensional (3D) scanning devices in general, and more particularly to improved methods and apparatus for 3D scanning of the human body form.
Methods and apparatus for 3D scanning of the human body form are known. Systems embodying such methods and apparatus are commercially-available from Real 3D, Inc. of Orlando, Fla., Textile/Clothing Technology Corporation of Cary, N.C., and Cyberwave Laboratory Inc. of Monterrey, Calif.
Such systems generally employ a beam of light that is reflected off a human subject and measured by a detector which receives the reflected beam. The point of contact between the reflected beam and the human subject is then determined in three dimensions. However, these systems generally require the human subject being scanned remove his/her clothing prior to scanning a wear a special tight-fitting garment having proper reflection properties with respect to the employed wavelength in order to ensure that the points of contact are of the human body form, and not of external garments, thus providing a more accurate scan.
By way of explanation, a beam of energy, such as light, impacting a surface of a given material generally interacts with the material in any of three ways: reflection, transmission, and absorption. A reflected beam is reflected from the surface at an angle of reflection equal to the impact angle in the case of specular reflection or a multitude of angles for the case of disperse reflection. A transmitted beam is transmitted through the material and emerges from the back surface of the material. The energy of an absorbed beam is at least partially absorbed by the material. A beam may be partially reflected, partially transmitted, and partially absorbed by the material such that the energy of the reflected beam, the amount of energy absorbed by the material, and the energy of the beam emerging from the back side of the material added together equals the initial impact energy of the source beam.
The ratio between the transmission (T) and reflection (R) properties of a material with respect to a given beam wavelength depend in part on such parameters as angle of impact, beam cross-section, and collimation. While the T/R ratio varies between 0 to ∞, it will typically have a measurable finite value. Current scanning techniques implicitly assume working conditions of either R greater than  greater than T for scanning an exposed surface or, for xe2x80x9csee-throughxe2x80x9d scanning of a surface through an outer layer of material R greater than  greater than T for the inner surface and T greater than  greater than R for the outer layer of material, or effectively transparent to the radiation employed. However, human skin and a large variety of materials found in clothing exhibit an R≈T behavior for a variety of wavelengths. Experimentation has shown that where an inner or target surface (I), such as skin, is scanned through an outer layer of material (O), such as clothing, the ratio xcex5 of the intensity of the beam reflected by the inner surface (IRB) to that of the beam reflected by the outer layer (ORB) may be expressed as IRB=xcex5xc2x7ORB with 0.01 less than xcex5 less than 0.5. Such a ratio does not comply with the assumptions of surface scanning or xe2x80x9csee-throughxe2x80x9d scanning described above. Thus, current scanning techniques do not exist that allow the human body form to be scanned while the human subject is wearing normal clothing as they work under an implicit assumption of xcex5 less than  less than 1, compatible with surface scanning assumptions only.
The disclosures of all patents, patent applications, and other publications mentioned in this specification and of the patents, patent applications, and other publications cited therein are hereby incorporated by reference.
The present invention seeks to provide improved methods and apparatus for 3D scanning of the human body form that allows for a subject to be scanned while wearing normal, loose-fitting clothing. Two reflections are generated for each scanned point, an inner surface reflection IRB from the subject""s skin and an outer layer reflection ORB from the subject""s clothing, exploiting the difference in the T/R characteristics of clothing and human skin under suitable conditions. In order to distinguish between the skin-reflected beam IRB and the clothes-reflected beam ORB in the equation IRB=xcex5xc2x7ORB the value of xcex5 is optimized for various clothing types, and signal processing techniques are used to extract IRB from the combined reflected beam signals. The T/R characteristic differences vary with the type of clothing and may be global (uniform) or local, with a particular fabric exhibiting a random or quasi-random local variation in its ability to transmit radiation due to differences in color, pattern, or texture.
There is thus provided in accordance with a preferred embodiment of the present invention a method for scanning an inner surface through an outer layer of material, the method including the steps of a) creating an energy beam with a wavelength, intensity, cross-section, and impact angle that, when impacted onto the outer layer of material, is sufficient to be at least partly reflected by the outer layer of material, thereby forming an outer-layer reflected beam, to be at least partly transmitted in a first direction through the outer layer of material and onto the inner surface, to be at least partly reflected by the inner surface, thereby forming an inner-surface reflected beam, and to be at least partly transmitted in a second direction through the outer layer of material, b) impacting the energy beam onto the outer layer of material, c) detecting the outer-layer reflected beam and inner-surface reflected beam, d) distinguishing between the outer-layer reflected beam and inner-surface reflected beam, and e) determining from the inner-surface reflected beam a point of incidence between the energy beam and the inner surface in three dimensions.
Further in accordance with a preferred embodiment of the present invention the method further includes performing steps a)-e) a plurality of times, thereby yielding a plurality of the points of incidence.
Still further in accordance with a preferred embodiment of the present invention steps a)-e) are performed upon a clothed human body.
Additionally in accordance with a preferred embodiment of the present invention the wavelength is between 400 to 2000 nm, the cross-section is between 0.005 to 3 cm, the intensity is between 0.02 to 100 mW, and the impact angle is between 0xc2x0 to 85xc2x0.
Moreover in accordance with a preferred embodiment of the present invention the distinguishing step includes distinguishing using either of time-domain analysis and spatial-domain analysis.
Further in accordance with a preferred embodiment of the present invention the energy beam has a repetition rate between 11 Hz to 80 MHz.
There is also provided in accordance with a preferred embodiment of the present invention apparatus for scanning an inner surface through an outer layer of material including an energy beam source operative to a) create an energy beam with a wavelength, intensity, cross-section, and impact angle that, when impacted onto the outer layer of material, is sufficient to be at least partly reflected by the outer layer of material, thereby forming an outer-layer reflected beam, to be at least partly transmitted in a first direction through the outer layer of material and onto the inner surface, to be at least partly reflected by the inner surface, thereby forming an inner-surface reflected beam, and to be at least partly transmitted in a second direction through the outer layer of material and b) impact the energy beam onto the outer layer of material, a detection unit operative to detect the outer-layer reflected beam and inner surface reflected beam, and a processing unit operative to distinguish between the outer-layer reflected beam and inner-surface reflected beam and determine from the inner-surface reflected beam a point of impact between the energy beam and the inner surface in three dimensions.